Built with specially-formulated concrete made of volcanic ash, this micro-house in Tokyo maximizes space through vertical construction. When Tokyo-based architecture firm Atelier TEKUTO received a brief from their clients to build a distinctive, environmentally-conscious concrete home, they embarked on a two-and-a-half year journey of spacial and material exploration. Built in 2015, the result—the R Torso C project—recently won the Overall Excellence Award and first place in the low-rise buildings category at the 2017 American Concrete Institute Awards.